Akage,
I'm afraid you're running on information from an old wives tale... We've done a lot of research including a pilot study of the demand valve method of oxygen therapy that also supports hyperventilation collecting data on over 366 aborts using this method... We observed 99% efficacy and very short abort times during this pilot study, but not one instance of blackout or any other adverse events!
CH'ers can and will get dizzy using this method of oxygen therapy. They will also encounter the other symptoms of paresthesia including a very slight tingling or prickling of the fingertips, lips and back of the neck, but nobody I know of has yet to blackout or become unconscious while using this procedure to abort a cluster headache.
These symptoms are the best indication the user has hyperventilated long enough and deep enough to push his or her system into respiratory alkalosis... the fastest way to abort a cluster headache reliably in a very short period of time... like an average of 7 minutes for CH between 3 and 9 on the 10-Point headache pain scale.
I've over 3000 hours flying Navy fighters and all of that flight time was spent breathing 100% oxygen at times at flow rates up to and above 50 liters/minute... I never lost consciousness and always brought the jet back for a safe landing ashore or a trap aboard ship.
I've also used oxygen therapy at flow rates that support hyperventilation at flow rates up to 60 liters/minute with a Flotec InGage™ oxygen regulator and O2PTIMASK™ and with an Oxygen Demand Valve since 2005.
I'm a CCH'er and averaged 2.5 aborts a day so that works out to over 4500 aborts with this method of oxygen therapy and I've yet to black out...
If you're going to Europe, your CGA-540 regulator will be useless... I know... I travel to the UK, Norway, Switzerland and Germany frequently on matters involving CH. The UK has a different standard cylinder attach fitting than Norway, Germany and Switzerland.
You'll also need to do some research on the type bayonet quick disconnect fittings used in each country to attach a demand valve as your DISS fitting will not work either.
I had an DISS to DIN quick disconnect adapter fabricated for me by Flotec Inc. that works well in Germany shown in the photo below attached to a Linde Integrated Valve (LIV) with a DIN female bayonet fitting for use with an oxygen demand valve.
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Each Non-EU and all the EU countries have a different standard for oxygen cylinder attach fittings and demand valve hose fittings... and DISS isn't one of them.
If you're only going to one country and can arrange to carry a LIV from Linde, call the folks at Flotec and you may have time for them to fabricate one of these adapters for you.
Regarding CGA-540 and CGA-870 regulators with selectable (click type) flow rates and or DISS... All US standard oxygen regulators are regulated to a fixed pressure of 50 psi unless special ordered otherwise.
DISS check valve fittings draw oxygen from downstream of this first stage fixed regulator that reduces cylinder pressure down to 50 psi and so does the flow rate selector. These selectors essentially offer a range of selectable orifices to control the flow rates... big openings for high flow rates and small openings for low flow rate.
Hope this helps.
Take care,
V/R, Batch